Copolyester-carbonate resins are members of the tough thermoplastic family of resins which, due to their many advantageous mechanical and physical properties, are finding increasing use as thermoplastic engineering materials. These copolyester-carbonate resins exhibit, for example, excellent properties of toughness, flexibility, impact strength, optical clarity, and high heat distortion temperatures. The conventional copolyester-carbonates may be produced by the coreaction of a dihydric phenol, a dicarboxylic acid or an ester forming reactive derivative thereof, and a carbonate precursor. These conventional copolyester-carbonates as well as methods for their preparation are disclosed inter alia in U.S. Pat. No. 3,169,121.
Unfortunately, these conventional copolyester-carbonates are rather difficult to process. It would, therefore, be highly desirable to provide copolyester-carbonat resins which are generally similar in many respects to conventional copolyester-carbonates and also exhibit improved processability.
It is, therefore, an object of the instant invention to provide copolyester-carbonate resins exhibiting improved processability.